Silicon process compatible trench magnetic device

DOMESTIC PRIORITY

0001This application claims priority to U.S. application Ser. No. 14/200,503, filed Mar. 7, 2014, which is incorporated herein by reference in its entirety.

BACKGROUND

0002The present invention relates generally to semiconductor integrated magnetic devices, and more specifically, to a toroidal trench inductor.

0003When constructing a semiconductor integrated magnetic device using a magnetic film, it is desirable to make the magnetic film sufficiently thick to obtain desirable operating characteristics for a given frequency of operation. However, the thickness of a single magnetic layer that is required for a given operating frequency of the magnetic device may result in the build-up of eddy currents in the magnetic material during operation, thereby resulting in some loss. As such, the magnetic film is typically made sufficiently thin to avoid eddy current losses, but with the tradeoff of lower energy storage ability.

0004The energy storage of an integrated magnetic device can be increased, however, by building a magnetic structure using a stack of alternating thin magnetic and insulating films, wherein the magnetic layers are separated by a thin insulating layer. In general, the use of multiple layers of magnetic material separated by layers of insulating material serves to prevent the build-up of eddy currents in the magnetic material, while providing an effective thickness of magnetic material, which is sufficient to obtain the desired operating characteristics for a given frequency of operation.

0005Conventional techniques for building multilayer magnetic-insulator structures include sputtering techniques. In general, a sputtering process includes forming a multilayer stack by alternately sputtering layers of a magnetic material and a dielectric material, patterning a photoresist layer to form an etch mask, using the etch mask to etch the multilayer stack of magnetic-insulating layers and remove unwanted regions of the multilayer stack, and then removing the etch mask. While sputtering can be used to build stacks of magnetic-insulating layers, the material and manufacturing costs for sputtering are high.

BRIEF SUMMARY

0006According to an exemplary embodiment, a method of integrating an inductor into a semiconductor is provided. The method includes providing a circular or other closed loop trench in a substrate, in which the trench is formed with sidewalls connected by a bottom surface in the substrate. The method includes depositing a first insulator layer on the sidewalls of the trench so as to coat the sidewalls and the bottom surface, and depositing a conductor layer on the sidewalls and the bottom surface of the trench so as to coat the first insulator layer in the trench such that the conductor layer is on top of the first insulator layer in the trench. A first magnetic layer is deposited on the sidewalls and the bottom surface of the trench so as to coat the first insulator layer in the trench without filling the trench. The first magnetic layer deposited on the sidewalls forms an inner closed magnetic loop and an outer closed magnetic loop within the trench. An interior conductor path is formed by the conductor layer at an inside wall of the trench, such that the interior conductor path connects to a first exterior conductor connection. A second exterior conductor connection separately connects to the conductor layer formed on an outside wall of the trench. An electrical path from the first exterior conductor connection to the second exterior connection by way of the conductor layer in the trench forms a continuous electrical path that passes through the inner and outer closed magnetic loops.

0007According to another exemplary embodiment, an integrated inductor in a semiconductor is provided. The integrated inductor includes a circular or other closed loop trench in a substrate, in which the trench is formed with sidewalls connected by a bottom surface in the substrate. A first insulator layer is deposited on the sidewalls of the trench so as to coat the sidewalls and the bottom surface. A conductor layer is deposited on the sidewalls and bottom surface of the trench so as to coat the first insulator layer in the trench such that the conductor layer is on top of the first insulator layer in the trench. A second insulator layer is deposited on top of the conductor layer on the sidewalls and the bottom surface of the trench. A first magnetic layer is deposited on the sidewalls and the bottom surface of the trench so as to coat the second insulator layer in the trench without filling the trench. The first magnetic layer deposited on the sidewalls forms an inner closed magnetic loop and an outer closed magnetic loop within the trench. An interior conductor path is formed by the conductor layer at an inside wall of the trench, such that the interior conductor path connects to a first exterior conductor connection. A second exterior conductor connection separately connects to the conductor layer formed on an outside wall of the trench. An electrical path from the first exterior connection to the second exterior connection by way of the conductor layer in the trench forms a continuous electrical path that passes through the inner and outer closed magnetic loops.

0008According to another exemplary embodiment, a method of integrating an inductor into a semiconductor is provided. The method includes providing a circular or other closed loop trench in a substrate, in which the trench is formed with sidewalls connected by a bottom surface in the substrate such that the trench forms a closed loop formation in the substrate. The method includes forming a first through silicon via (TSV) outside of the closed loop formation, forming a second through silicon via near a center of the closed loop formation, and depositing a first magnetic material layer on the sidewalls of the trench so as to coat the sidewalls and the bottom surface without filling the trench. The first magnetic material layer deposited on the sidewalls forms a first inner closed magnetic loop and a first outer closed magnetic loop within the trench. An electrical connection is formed between the first and second through silicon via, so as to define a continuous electrical path that passes from the first through silicon via to the second through silicon via and passes through the inner and outer closed magnetic loops.

0009Additional features and advantages are realized through the techniques of the present invention. Other embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed invention. For a better understanding of the invention with the advantages and the features, refer to the description and to the drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

0010The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The forgoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

0011<figref idref="DRAWINGS">FIGS. 1A through 1E</figref> illustrate a fabrication process to form an embedded toroidal trench inductor structure according to an embodiment, in which:

0012<figref idref="DRAWINGS">FIG. 1A</figref> illustrates a cross-sectional view and its corresponding top view of fabricating the toroidal trench inductor structure according to an embodiment.

0013<figref idref="DRAWINGS">FIG. 1B</figref> illustrates a cross-sectional view and its corresponding top view of fabricating the toroidal trench inductor structure according to an embodiment.

0014<figref idref="DRAWINGS">FIG. 1C</figref> illustrates a cross-sectional view and its corresponding top view of fabricating the toroidal trench inductor structure according to an embodiment.

0015<figref idref="DRAWINGS">FIG. 1D</figref> illustrates a cross-sectional view and its corresponding top view of fabricating the toroidal trench inductor structure according to an embodiment.

0016<figref idref="DRAWINGS">FIG. 1E</figref> illustrates a cross-sectional view and its corresponding top view of fabricating the toroidal trench inductor structure according to an embodiment.

0017<figref idref="DRAWINGS">FIGS. 2A through 2F</figref> illustrate a fabrication process to form an embedded toroidal trench inductor structure according to an embodiment, in which:

0018<figref idref="DRAWINGS">FIG. 2A</figref> illustrates a cross-sectional view and its corresponding top view of fabricating the toroidal trench inductor structure according to an embodiment.

0019<figref idref="DRAWINGS">FIG. 2B</figref> illustrates a cross-sectional view and its corresponding top view of fabricating the toroidal trench inductor structure according to an embodiment.

0020<figref idref="DRAWINGS">FIG. 2C</figref> illustrates a cross-sectional view and its corresponding top view of fabricating the toroidal trench inductor structure according to an embodiment.

0021<figref idref="DRAWINGS">FIG. 2D</figref> illustrates a cross-sectional view and its corresponding top view of fabricating the toroidal trench inductor structure according to an embodiment.

0022<figref idref="DRAWINGS">FIG. 2E</figref> illustrates a cross-sectional view and its corresponding top view of fabricating the toroidal trench inductor structure according to an embodiment.

0023<figref idref="DRAWINGS">FIG. 2F</figref> illustrates an optional process that continues from <figref idref="DRAWINGS">FIG. 2C</figref> according to an embodiment.

0024<figref idref="DRAWINGS">FIGS. 3A and 3B</figref> together illustrate a method of integrating an inductor into a semiconductor such as the substrate according to an embodiment.

0025<figref idref="DRAWINGS">FIG. 4</figref> illustrates a method of integrating an inductor into a semiconductor according to an embodiment.

0026<figref idref="DRAWINGS">FIG. 5</figref> illustrates a cross-sectional view that combines the embedded toroidal trench inductor structure in <figref idref="DRAWINGS">FIG. 1</figref> with the though silicon vias in <figref idref="DRAWINGS">FIG. 2</figref> according to an embodiment.

DETAILED DESCRIPTION

0027For high frequency integrated inductors, one needs a closed loop of magnetic material and a coil that passes through the closed loop. According to embodiments, examples are provided of a toroidal ring of magnetic material embedded flat in the substrate with a coil around the magnetic material.

0028In the present disclosure, this is done by making a circular or other closed loop trench and depositing magnetic material on the walls of the trench. There are two closed loops of magnetic material made at once: the interior and exterior walls. So instead of depositing twice to achieve one closed magnetic loop, the process herein deposits once and makes two closed loops of magnetic material. If there is more than one concentric trench loop, the result is that the process makes two more layers of magnetic material for each additional trench. This means one can get many (for multiple concentric loops) thin layers of magnetic material in one deposition step. The advantage of many thin magnetic layers is that the eddy current losses in the magnetic film are determined by the thickness of a film, while the overall inductance and magnetic saturation current increase with the amount of magnetic material. The ring trench approach allows for a high inductance in a small substrate surface area. It is noted that the trench should not be filled with conducting magnetic material as this shorts the interior and exterior walls of the magnetic layers together.

0029The coil (i.e., conductor material such as copper) has to pass through these loops of magnetic material. There are two ways to accomplish this:

00301. Depositing conductor (usually copper) on the side walls and bottom of the trench so that there is path down the side of the trench, across the bottom and up the interior wall. This is like wrapping a very wide flat wire through the torroid.

00312. Create separately silicon through visa (TSVs) by techniques understood by one skilled in the art and have one inside the magnetic loop and one outside, and then connect the two at the wafer back surface. Note that embodiments may use more TSVs and/or may use more copper layers with insulation in between to create additional coils and coil turns.

0032In order to facilitate the use of thin film magnetic material, embodiments ensure that the magnetic easy axis is oriented perpendicular to the wafer (substrate) surface. This is accomplished by applying a magnetic field perpendicular to the substrate plane during depositions and anneals. (Conventional systems have the applied magnetic filed and induced magnetic easy axis in the plane field of the substrate.)

0033Embodiments deposit a thin nonmagnetic layer (examples: NiP, Ta, TaN, TiN, Cu, Ni or other metal or insulator between 5 nm (nanometers) and 1000 nm) on top of the magnetic materials on the trench walls, and the deposit a second layer of magnetic material on the trench walls. A bilayer of magnetic material with a thin nonmagnetic separator has better magnetic domain properties. If the separator is insulating, implementations achieve twice the magnetic thickness without increased eddy current loss. If the separator is insulating, implementations may deposit an additional conducting seed layer when the magnetic layer is to be electroplated.

0034Some implementations may have more than one coil passing through the magnetic loops done by: 1) two layers of copper on the trench walls separated by insulator; 2) copper on the trench walls and coil(s) made using TSVs and substrate surface wires; and/or 3) two or more coils made using TSVs and substrate surface wires.

0035Having two or more coils allows for transformer and coupled inductor applications. Also, implementations may connect the coils in series to achieve more turns and a higher inductance.

0036In some implementations, the magnetic materials are insulated from the substrate, and the magnetic materials are insulated from the conductor (which improves performance). Also, after the magnetic material is deposited, the trench may then be filled in with a nonmagnetic, non-conducting material such as oxide or polymer. This allows wiring on the top surface and is required if the inductor is not connected to another substrate that contains a path to close the inductor coil loop. The trench loops may be circular which provides better magnetic properties. Also, the layers of magnetic material may be deposited by electroplating: this requires deposition of a continuous conducting seed layer that is removed after the magnetic film deposition. The magnetic properties are better (fewer domain walls) if the magnetic material is continuous from the walls across the bottom of the trench.

0037Now turning to the figures, <figref idref="DRAWINGS">FIGS. 1A, 1B, 1C, 1D, and 1E</figref> (generally referred to as <figref idref="DRAWINGS">FIG. 1</figref>) illustrate a schematic to fabricate an embedded toroidal trench inductor structure <b>10</b> according to an embodiment. For the toroidal trench inductor structure <b>10</b>, <figref idref="DRAWINGS">FIGS. 1A through 1E</figref> illustrate cross-sectional views on the left and corresponding top views on the right.

0038<figref idref="DRAWINGS">FIG. 1A</figref> illustrates etching a substrate <b>100</b> to eventually form two concentric closed loop rings of magnetic material in per single (circular and/or closed loop) trench <b>150</b>. The substrate <b>100</b> may be silicon. Only one trench is shown but it is understood that two or more concentric (circular) trenches may be utilized as discussed herein.

0039<figref idref="DRAWINGS">FIG. 1B</figref> illustrates depositing an oxide insulator <b>101</b> in the trench <b>150</b>. The sidewalls and bottom surface of the trench <b>150</b> are coated with the oxide insulator <b>101</b>. The oxide insulator <b>101</b> is also deposited on the top surface <b>160</b> of the substrate. A damascene groove <b>162</b> is etched into the oxide insulator <b>101</b> to define the wiring traces for connection to the inductor at the trench interior and exterior. Other materials are also deposited in the damascene groove <b>162</b> as discussed further in <figref idref="DRAWINGS">FIG. 1</figref>. Note that the oxide insulator <b>101</b> is deposited so as not to fill the trench <b>150</b> but to leave a cavity in the trench. The oxide insulator <b>101</b> material may have a thickness of 50 nm (nanometers) to 1000 nm on each sidewall and a thickness of 50 nm to 1000 nm on the bottom surface.

0040<figref idref="DRAWINGS">FIG. 1C</figref> illustrates (optionally) depositing an adhesion layer/liner <b>102</b> on top of the coated oxide insulator <b>101</b> in the circular trench <b>150</b> and also on the top surface <b>160</b> of the substrate <b>100</b>. Examples of the adhesion layer/liner <b>102</b> include Ti/TiN, Ta/TaN, etc. The adhesion layer/liner <b>102</b> is deposited (and patterned) on the top surface <b>160</b> of the substrate <b>100</b> in the elongated pattern wiring trace <b>162</b> so as to fit within the rectangular shape of the (previously deposited) oxide insulator <b>101</b> material. Note that the adhesion layer/liner <b>102</b> is deposited on the sidewalls and bottom surfaces of the trench <b>150</b> so as to leave a cavity in the trench <b>150</b>. The adhesion layer/liner <b>102</b> may have a thickness of 10 nm to 1000 nm on each sidewall and a similar thickness on the bottom surface.

0041After depositing the adhesion layer/liner <b>102</b> in the trench <b>150</b>, a conductor layer <b>103</b> is deposited on the coated adhesion layer/liner <b>102</b> in the trench <b>150</b> and also on the top surface <b>160</b> of the substrate <b>100</b>. A seed metal may be applied first to grow the conductor layer <b>103</b>. Examples of the conductor layer <b>103</b> include copper, aluminum, Ni, NiFe, Co, CoW. Note that if a magnetic film is to be plated, a magnetic seed material (metal) is desirable first (even in <figref idref="DRAWINGS">FIG. 2</figref> below), and in one case, the magnetic seed may be a bilayer with copper for conductivity and then magnetic material. The conductor layer <b>103</b> is deposited on the top surface <b>160</b> of the substrate <b>100</b> so as to fill the damascene groove or wiring trace <b>162</b>. Excess conductor and seed on the surface outside the groove <b>162</b> can then be removed by CMP (chemical-mechanical-polishing). Alternatively, the damascene groove <b>162</b> can be omitted from the design, and the conductor plating region restricted to the wiring traces may be formed with a photopatterned photoresist layer in which case the excess seed is removed by etching following the removal of the photoresist. Note that the conductor layer <b>103</b> is deposited so as to leave a cavity in the trench <b>150</b>. The conductor layer <b>103</b> may have a thickness of 50 nm to 1000 nm on each sidewall on the bottom surface. Since there may be some reduction in thickness on the trench bottom, the deposition thickness may be chosen to achieve a minimum thickness of 25 nm on the trench bottom. As a result of deposition, the conductor layer <b>103</b> has an inner closed loop of conductor material lining the inner sidewall and an outer closed loop of conductive material lining the outer sidewall of the trench <b>150</b>. The inner closed loop of the conductor layer <b>103</b> and the outer closed loop of the conductor layer <b>103</b> are connected by the bottom surface of conductor layer <b>103</b> at the bottom of the trench.

0042<figref idref="DRAWINGS">FIG. 1D</figref> illustrates depositing a second insulator <b>104</b> on top of the coated conductor layer <b>103</b> in the trench <b>150</b> and also on the top surface <b>160</b> of the substrate <b>100</b>. Examples of the insulator <b>104</b> include silicon dioxide, SiN, SiCNi, polyimide, and polybenzoxazole (PBO). The insulator <b>104</b> is deposited on the top surface <b>160</b> of the substrate <b>100</b> in the elongated pattern wiring trace <b>162</b> so as to fit within the rectangular shape of the (previously deposited) oxide insulator <b>101</b>, the adhesion layer/liner <b>102</b>, and conductor layer <b>103</b>. Note that the second insulator <b>104</b> is deposited in the trench <b>150</b> so as to leave a cavity in the trench <b>150</b>. The second insulator material <b>104</b> may have a thickness of 10 nm to 1000 nm on each sidewall and on the bottom surface.

0043After depositing the second insulator <b>104</b> within the trench <b>150</b>, a seed metal <b>105</b> is deposited on the coated insulator <b>104</b> in both the trench <b>150</b> and also on the top surface <b>160</b> of the substrate <b>100</b>. Examples of the seed metal <b>105</b> copper, aluminum, Ni, NiFe, Co, and CoW. The seed metal <b>105</b> is deposited on the top surface <b>160</b> of the substrate <b>100</b>. Note that the seed metal <b>105</b> is deposited in the trench <b>150</b> so as leave a cavity in the trench <b>150</b>. The seed metal <b>105</b> may have a thickness of 10 nm to 1000 nm on each sidewall and on the bottom surface.

0044A photomask <b>106</b> is deposited on the top surface <b>106</b> as a pattern for depositing a magnetic film <b>107</b>. The photomask <b>106</b> covers the entire substrate <b>100</b> (including the elongated pattern wiring trace <b>162</b>) except for the trench <b>150</b>. The magnetic film <b>107</b> is deposited on the coated seed metal <b>105</b> in the trench <b>150</b> and also on the top surface <b>160</b> of the substrate <b>100</b>. The magnetic film <b>107</b> is magnetic material. The magnetic film <b>107</b> is deposited and/or thermally annealed within (the presence) of a vertical (perpendicular to the substrate plane) magnetic field <b>120</b> (represented by an arrow) such that the magnetic film <b>107</b> has an induced magnetic anisotropy, which means that the easy axis of the magnetic film <b>107</b> is aligned with the magnetic field and is perpendicular to the (horizontal) plane of the substrate. The magnetic material of the magnetic film <b>107</b> may be deposited by electroplating. Examples of the magnetic film <b>107</b> include NiFe, CoWP, Fe, CoFeB, etc. The magnetic film <b>107</b> is not deposited on the top surface <b>160</b> of the substrate <b>100</b> in the elongated pattern <b>162</b> or at least is removed when the photomask <b>106</b> is removed. Note that the magnetic film <b>107</b> is deposited in the trench <b>150</b> so as to leave a cavity in the trench <b>150</b>. The magnetic film <b>107</b> may have a thickness of 100 nm to 3000 nm on each sidewall and on the bottom surface. If plating or deposition process limitations cause the film thickness to vary and be thinner on and near the bottom of the trench, this is undesirable. In this case, the inductor will still work albeit with smaller inductance even if the magnetic film <b>107</b> thickness is zero on the trench bottom. The magnetic film <b>107</b> has an inner closed loop of magnetic material lining the inner sidewall and an outer closed loop of magnetic material lining the outer sidewall of the trench <b>150</b>. These the inner and outer closed loops of magnetic film <b>107</b> are two magnetic laminate layers currently deposited in the trench <b>150</b>.

0045<figref idref="DRAWINGS">FIG. 1E</figref> illustrates removing the photomask <b>106</b>. A photopatterned insulator <b>108</b> is deposited to fill in the trench <b>150</b> and as an overcoat on top of the substrate <b>100</b>. Examples of the photopatterned insulator <b>108</b> may include photosensitive-polyimide (PSPI), polybenzoxazole (PBO), etc.

0046Two via openings <b>109</b>A and <b>109</b>B are opened (i.e., etched) down to the conductor layer <b>103</b> on the elongated rectangular pattern (portion) <b>162</b>, such that the conductor layer <b>103</b> is exposed at two separate locations on the elongated pattern <b>162</b>. The via opening <b>109</b>A is on the outside of the circular trench <b>150</b> while the via opening <b>109</b>B is in about the center of the circular formation made by the circular trench. The toroidal trench inductor structure <b>10</b> is complete and can be connected further by depositing wiring over the via openings <b>109</b>A and <b>109</b>B.

0047As noted above, the conductor layer <b>103</b> has the inner closed loop of conductive material lining the inner sidewall and the outer closed loop of conductive material lining the outer sidewall of the trench <b>150</b>, along with the bottom surface of conductor layer <b>107</b> connecting the inner and outer loops of conductor material. Via the elongated pattern <b>162</b>, the opening <b>109</b>A is configured so that one polarity (e.g., positive) of a voltage source electrically connects to the outer closed loop of conductor layer <b>103</b> while the opening <b>109</b>B is configured so that the opposite polarity (e.g., negative) of the voltage source electrically connects to the inner closed loop of the conductor layer <b>103</b>. When the voltage source is turned on, electrical current flows from the positive side of the voltage source, into the opening <b>109</b>A, through the elongated pattern <b>162</b>, down the outer closed loop of conductor layer <b>103</b> in the trench <b>150</b>, through the bottom conductor layer <b>103</b> on the bottom surface in the trench <b>150</b>, up the inner closed loop of conductor layer <b>103</b>, out the elongated pattern <b>162</b>, and out the opening <b>109</b>B back to the voltage source. Note that the elongated pattern wiring trace <b>162</b> has a first exterior conductor connection <b>164</b>A that connects (electrically) to the conductor layer <b>103</b> at the inside wall (i.e., the inner closed loop of the conductor layer <b>103</b>) of the trench <b>150</b>. Also, the elongated pattern wiring trace <b>162</b> has a second exterior conductor connection <b>164</b>B that separately (electrically) connects to the conductor layer <b>103</b> formed on an outside wall of the trench <b>150</b>.

0048According to another embodiment, <figref idref="DRAWINGS">FIGS. 2A, 2B, 2C, 2D, 2E, and 2F</figref> (generally referred to as <figref idref="DRAWINGS">FIG. 2</figref>) illustrate a schematic to fabricate an embedded toroidal trench inductor structure <b>20</b>. For the toroidal trench inductor structure <b>20</b>, <figref idref="DRAWINGS">FIGS. 2A through 2F</figref> illustrate cross-sectional views on the left and corresponding top views on the right.

0049<figref idref="DRAWINGS">FIG. 2A</figref> illustrates forming two through silicon vias (TSVs) <b>201</b>A and <b>201</b>B etched into a substrate <b>200</b> as understood by one skilled in the art. The substrate <b>200</b> (or <b>100</b> in <figref idref="DRAWINGS">FIG. 1</figref>) may be a silicon wafer. Other substrates may include glasses, SiO₂, polymers (such as polymide, SiC, tungsten carbide, titanium carbide, and N58), and aluminum oxide. The TSVs <b>201</b>A and <b>201</b>B are vertical electrical connections also referred to as vertical interconnect vias. The TSVs <b>201</b>A and <b>201</b>B are filled with conductor material <b>26</b> surrounded by insulating material <b>28</b>. When the substrate is not silicon, the through silicon vias (TSVs) can be replaced with other through-substrate-via structures, as the utilization of the through silicon via structure is not a requirement. An example would be the copper filled vias used with glass substrates.

0050Back end of line (BEOL) wiring <b>202</b> is deposited on top of the substrate <b>200</b> including the TSVs <b>201</b>A and <b>201</b>B. The BEOL wiring <b>202</b> may be metal wiring such as copper, aluminum, gold, etc. An optional handler <b>203</b> is attached to the top of the substrate <b>200</b> including the BEOL wiring <b>202</b>. The handler <b>203</b> is an additional substrate attached temporarily to the wafer with an adhesive to give structural support during processing of a thinned wafer. If the thinned wafer thickness is sufficient for mechanical stability during processing it may not be necessary. Handlers are most commonly silicon-thermal-expansion-matched borosilicate glass or silicon.

0051<figref idref="DRAWINGS">FIG. 2B</figref> shows that that the substrate <b>200</b> is flipped over and the substrate <b>200</b> (wafer) is thinned, e.g., by polishing, to expose the TSVs <b>201</b>A and <b>201</b>B. A circular trench <b>204</b> (as discussed above) is etched into the substrate <b>200</b> to form a ring. The exposed TSV <b>201</b>A is outside (i.e., to the exterior) of the trench <b>204</b>. The circular trench <b>204</b> encircles the TSV <b>201</b>B. Since the substrate (wafer) <b>200</b> has been flipped over, the previous bottom side will now be referred to as the top side, such that the handler <b>203</b> is now on the bottom side.

0052<figref idref="DRAWINGS">FIG. 2C</figref> illustrates depositing a blanket deposit of seed <b>205</b> in the trench <b>204</b>. The sidewalls and bottom surface of the trench <b>204</b> are coated with the seed <b>205</b>. The seed <b>205</b> is also deposited on a top surface <b>260</b> of the substrate <b>200</b>. Note that the seed <b>205</b> is deposited in the trench <b>204</b> so as to leave a cavity in the trench <b>204</b>. Examples of the seed <b>205</b> include Ti/TiN, TaTaN, Cu, Ni, NiFe, Co, CoW, and/or several of these materials deposited in sequence or other conducting materials. The seed <b>205</b> material may have a thickness of 10 to 1000 nm on each sidewall and on the bottom surface. Some reduction in thickness on the trench bottom due to process limitations can be tolerated as long as the film is continuous.

0053Additionally, photomask <b>206</b> is deposited and patterned on the substrate <b>200</b> in <figref idref="DRAWINGS">FIG. 2C</figref>. The photomask <b>206</b> covers the entire substrate <b>200</b> except for the trench <b>204</b>. A (first) magnetic film <b>207</b> is deposited on (and/or grown from) the seed <b>205</b> in the trench <b>204</b>. The magnetic film <b>207</b> is magnetic material. The magnetic film <b>207</b> is deposited and/or thermally annealed within (the presence) of a magnetic field <b>220</b> (represented by an arrow) such that the magnetic film <b>207</b> has an magnetic anisotropy or “easy axis” of the magnetic film <b>207</b> that is perpendicular to the substrate plane. The magnetic material of the magnetic film <b>207</b> may be deposited by electroplating. Examples of the magnetic film <b>207</b> include NiFe, CoWP, Fe, CoFeB, etc. The magnetic film <b>207</b> is not deposited on the top surface <b>260</b> of the substrate <b>200</b> except as desired to allow for alignment tolerances, or in the case when multiple concentric trenches are used, the magnetic material can be continuous between trenches. Note that the magnetic film <b>207</b> is deposited in the trench <b>204</b> so as to leave a cavity in the trench <b>204</b>. The magnetic film <b>207</b> may have a thickness of 100 to 3000 nm on each sidewall and on the bottom surface. If plating or deposition process limitations cause the film thickness to vary and be thinner on and near the bottom of the trench, this is undesirable. In this case, the inductor will still work albeit with smaller inductance even if the magnetic film thickness is zero on the trench bottom. The magnetic film <b>207</b> has an inner closed loop of magnetic material lining the inner sidewall and an outer closed loop of magnetic material lining the outer sidewall of the trench <b>204</b>.

0054In an alternate method, the magnetic film <b>207</b> is not a single magnetic layer but instead is formed as a coupled magnetic multilayer where the a first magnetic layer of half the intended thickness is deposited, then a nonmagnetic conductor such as NiP or Cu is deposited to a thickness between 10 nm and 1000 nm, and a second magnetic film making up the remaining magnetic material is deposited. An example is the NiFe/NiP/NiFe coupled magnetic film where the plating conditions are changed during electroplating to alter the material composition. Coupled magnetic films have improved magnetic domain properties as known to those skilled in the art.

0055<figref idref="DRAWINGS">FIG. 2D</figref> illustrates that the cavity in the magnetic film <b>207</b> in the trench <b>204</b> is going to be filled. Also, the photomask <b>206</b> is etched away and the seed <b>205</b> on the top surface <b>260</b> is etched away.

0056Now, a blanket of oxide <b>208</b> is deposited on the top surface <b>260</b>. The oxide layer <b>208</b> covers the entire the top surface <b>260</b> of the substrate <b>200</b>. The oxide layer <b>208</b> is deposited on the coated magnetic film <b>207</b> in the trench <b>204</b>. Note that the oxide layer <b>208</b> is deposited in the trench <b>204</b> so as to leave a cavity in the trench <b>204</b>. The oxide layer <b>208</b> may have a thickness of 10 nm to 1000 nm on each sidewall and on the bottom surface.

0057A blanket of seed <b>209</b> is deposited on the top surface <b>260</b>. The seed <b>209</b> covers the entire the top surface <b>260</b> of the substrate <b>200</b>. The seed <b>209</b> is deposited on the oxide layer <b>208</b> in the trench <b>204</b>. Note that the seed <b>209</b> is deposited in the trench <b>204</b> so as to leave a cavity in the trench <b>204</b>. The seed <b>209</b> material may have a thickness of 10 to 1000 nm on each sidewall on the bottom surface.

0058Also, a photomask <b>210</b> is deposited and patterned on the top surface <b>260</b> of the substrate <b>200</b>, so as to leave an opening for depositing a (second) magnetic film <b>211</b> in the trench <b>204</b>. The magnetic film <b>211</b> is deposited on (and/or grown from) the coated seed <b>209</b>. The magnetic film <b>211</b> is magnetic material (which may be the same magnetic material or different magnetic material than the magnetic film <b>207</b>). The magnetic film <b>211</b> is deposited within (the presence) of the magnetic field <b>220</b> (represented by an arrow) such that the magnetic film <b>207</b> has an anisotropy direction perpendicular to the wafer surface. Examples of the magnetic film <b>211</b> include NiFe, CoWP, Fe, CoFeB, etc. The magnetic film <b>211</b> is not deposited on the top surface <b>260</b> of the substrate <b>200</b>, and the magnetic film <b>211</b> leaves a cavity in the trench <b>204</b>. The magnetic film <b>211</b> may have a thickness 100 to 3000 nm on each sidewall and on the bottom surface. If plating or deposition process limitations cause the film thickness to vary and be thinner on and near the bottom of the trench this is undesirable. The inductor will still work albeit with smaller inductance even if the magnetic film thickness is zero on the trench bottom. The magnetic film <b>211</b> also has an inner closed loop of magnetic material lining the inner sidewall and an outer closed loop of magnetic material lining the outer sidewall of the trench <b>204</b>.

0059The process discussed in <figref idref="DRAWINGS">FIG. 2D</figref> may be repeated (multiple times) to build up more laminated magnetic film layers <b>211</b> in the trench <b>204</b>. Currently, two magnetic film layers <b>207</b> and <b>211</b> are shown which result in four closed loops of magnetic material.

0060<figref idref="DRAWINGS">FIG. 2E</figref> illustrates that the photomask <b>210</b> is etched away and the seed <b>209</b> (only) on the top surface <b>260</b> is etched away. An insulator <b>228</b> is applied on the top surface <b>260</b> and to fill the trench <b>204</b>. The insulator <b>228</b> and insulator <b>208</b> are patterned/etched to expose the inductor electrical contacts which are the TSVs <b>201</b>A and <b>201</b>B. Examples of the insulator <b>228</b> may include photosensitive-polyimide (PSPI), polybenzoxazole (PBO), etc. Although not shown, the process may continue by adding wiring, pads, and solder balls as understood by one skilled in the art. When complete, the handler <b>203</b> is removed.

0061Optionally, <figref idref="DRAWINGS">FIG. 2D</figref> (and <figref idref="DRAWINGS">FIG. 2E</figref>) may be skipped in one implementation and the process may flow directly from <figref idref="DRAWINGS">FIG. 2C</figref> to <figref idref="DRAWINGS">FIG. 2F</figref>. In that case, <figref idref="DRAWINGS">FIG. 2F</figref> illustrates that that the deposition of the magnetic film <b>207</b> in the trench <b>204</b> leaves a cavity to be filled. Also, the photomask <b>206</b> is etched away and the seed <b>205</b> on the top surface <b>260</b> is etched away. The insulator <b>228</b> is applied on the top surface <b>260</b> and to fill the trench <b>204</b>. The insulator <b>228</b> is patterned to expose the inductor electrical contacts which are the TSVs <b>201</b>A and <b>201</b>B. Examples of the <b>228</b> may include photosensitive-polyimide (PSPI), polybenzoxazole (PBO), etc. Although not shown, the process may continue with by adding wiring, pads, and solder balls as understood by one skilled in the art. When complete, the handler <b>203</b> is removed. The implementation in <figref idref="DRAWINGS">FIG. 2F</figref> only has one application/deposition of magnetic film layer <b>207</b> which results into two closed loops of magnetic material (i.e., two magnetic laminate layers).

0062It is noted that the magnetic materials discussed herein may be deposited by any method such as sputtering, evaporation, CVD, electroplating, and electroless plating. Further, <figref idref="DRAWINGS">FIG. 5</figref> illustrates a cross-sectional view <b>500</b> that combines the embedded toroidal trench inductor structure <b>10</b> with the TSV <b>201</b>A and <b>201</b>B from <figref idref="DRAWINGS">FIG. 2</figref> according to an embodiment. Reference can be made to <figref idref="DRAWINGS">FIGS. 1 and 2</figref> discussed above. The inductor <b>10</b> shown in <figref idref="DRAWINGS">FIG. 5</figref> provides a two coil structure that is useful for coupled inductors. As discussed in <figref idref="DRAWINGS">FIG. 1E</figref>, the elongated pattern wiring trace <b>162</b> (via the first exterior conductor connection <b>164</b>A) electrically connects to the conductor layer <b>103</b> at the inside wall (i.e., the inner closed loop of the conductor layer <b>103</b>) of the trench <b>150</b>. Also, the elongated pattern wiring trace <b>162</b> (via the second exterior conductor connection <b>164</b>B) separately connects electrically to the conductor layer <b>103</b> formed on an outside wall of the trench <b>150</b>. In addition to that (first) electrical path formed by the wiring trace <b>162</b> in <figref idref="DRAWINGS">FIG. 1</figref>, the through silicon vias <b>201</b>A and <b>201</b>B along with BEOL <b>202</b> for a separate electrical path. For example, the first through silicon via (TSV) <b>201</b>A is formed outside of the circular trench <b>150</b>, and the second through silicon <b>201</b>B is formed near the center of the circular trench <b>150</b>. An electrical connection is formed between the first and second through silicon vias (and the BEOL <b>202</b>), so as to define a continuous electrical path that passes from the first through silicon via <b>201</b>A to the second through silicon via <b>201</b>B and passes through the inner and outer closed magnetic loops.

0063<figref idref="DRAWINGS">FIGS. 3A and 3B</figref> together illustrate a method <b>300</b> of integrating the inductor <b>10</b> into a semiconductor such as the substrate <b>100</b> according to an embodiment. Reference can be made to <figref idref="DRAWINGS">FIG. 1</figref>. The method includes providing a circular trench <b>150</b> in the substrate <b>100</b>, where the trench <b>150</b> is formed with sidewalls connected by a bottom surface in the substrate <b>150</b> at block <b>305</b>.

0064At block <b>310</b>, a first insulator layer <b>101</b> is deposited on the sidewalls of the trench <b>150</b> so as to coat the sidewalls and the bottom surface. At block <b>315</b>, a conductor layer <b>103</b> is deposited on the sidewalls and the bottom surface of the trench <b>150</b> so as to coat the first insulator layer <b>101</b> in the trench such that the conductor layer <b>103</b> is on top of the first insulator layer <b>101</b> in the trench.

0065At block <b>320</b>, a second insulator layer <b>104</b> is deposited on top of the conductor layer <b>103</b> on the sidewalls and the bottom surface of the trench <b>150</b>. At block <b>325</b>, magnetic material <b>107</b> is deposited on the sidewalls and the bottom surface of the trench <b>150</b> so as to coat the second insulator layer <b>104</b> in the trench <b>150</b> without filling the trench. Note that the seed layer <b>105</b> is optional for electroplating.

0066At block <b>330</b>, the conductor layer <b>103</b> deposited on the sidewalls forms an inner closed loop (i.e., the closed loop of conductor layer <b>103</b> material on the inner wall of the trench <b>150</b>) and an outer closed loop (i.e., the closed loop of conductor layer <b>103</b> material on the outer wall of the trench <b>150</b>) within the trench <b>150</b> connected by a bottom conductor layer <b>103</b> on the bottom surface of the trench <b>150</b>, in which the inner closed loop, the outer closed loop, and the bottom conductor layer <b>130</b> form an interior conductor path inside the trench <b>150</b>, such that the interior conductor path passes underneath and around sides of the magnetic material <b>107</b> in the trench <b>150</b>. Note that the magnetic material <b>107</b> also has its own inner closed loop and outer closed loop easier seen when viewed from a top view.

0067At block <b>335</b>, the interior conductor path inside the trench <b>150</b> connects to an exterior conductor path (which is the wiring trace <b>162</b> of the conductor layer <b>130</b>), and the exterior conductor path separately connects to the inner loop of the conductor layer <b>103</b> (by the wiring trace <b>162</b> of the conductor layer <b>103</b> on the surface <b>160</b> encircled by the trench <b>150</b> connecting to the inner wall of the conductor layer <b>103</b> in the trench <b>150</b>) and the outer loop of the conductor layer <b>103</b> (by the elongated pattern <b>162</b> of the conductor layer <b>103</b> on the surface <b>160</b> not encircled by the trench <b>150</b> connecting to the outer wall of the conductor layer <b>103</b> in the trench <b>150</b>).

0068The exterior conductor path is a wiring trace <b>162</b> of the conductor layer <b>103</b> applied on a top surface <b>160</b> of the substrate <b>100</b>. The wiring trace <b>162</b> of the conductor layer <b>130</b> is concurrently deposited on the top surface of substrate <b>100</b> (but is not in the trench <b>150</b>) when depositing the conductor layer <b>130</b> inside the trench <b>150</b>.

0069The method can continue by depositing a third insulator layer (just like insulator layer <b>104</b> but within the previously deposited magnetic material <b>107</b>) on the sidewalls and the bottom surface of the trench <b>150</b> so as to coat the magnetic material <b>107</b> in the trench <b>150</b> without filling the trench <b>150</b>, and then depositing a second magnetic material (just as the magnetic material <b>107</b> was previously deposited on/grown from the seed material <b>105</b>) on the sidewalls and the bottom surface of the trench <b>150</b> so as to coat the third insulator layer in the trench <b>150</b> without filling the trench <b>150</b>.

0070A magnetic field <b>120</b> aligned perpendicular to the substrate plane is applied while depositing the magnetic material <b>107</b> and/or during a subsequent thermal anneal causing the magnetic material to have an induced anisotropy perpendicular (i.e., vertical) to the plane of the substrate <b>100</b>.

0071The method where depositing the magnetic material <b>107</b> comprises a coupled magnetic film made by electroplating NiFe as the magnetic material, subsequently electroplating NiP, and then electroplating NiFe again in a (single) continuous electroplating process of the magnetic material <b>107</b>. An alternative method where the magnetic layer is a coupled magnetic film as known in the art where the magnetic film has sublayers made by depositing a magnetic material, subsequently electroplating a conducting nonmagnetic material, and then electroplating another magnetic layer. For eddy current purposes the two layers together need to be thin enough to avoid eddy current losses and then multiple pairs of these magnetic bilayers are built up separated by having an insulator in between. The nonmagnetic material would be a conductor which means one does not need to deposit a new adhesion layer and seed metal. Nonmagentic layers include Ni, Cu, NiP, Ta, Ti, and others.

0072<figref idref="DRAWINGS">FIG. 4</figref> illustrates a method <b>400</b> of integrating an inductor <b>20</b> into a semiconductor (substrate <b>200</b>) according to an embodiment. The method includes providing a circular trench <b>204</b> in the substrate <b>200</b>, where the trench <b>204</b> is formed with sidewalls connected by a bottom surface in the substrate <b>200</b> such that the trench forms a circular formation in the substrate <b>200</b> at block <b>405</b>.

0073A first through silicon via (TSV) <b>201</b>A is formed outside of the circular formation at block <b>410</b>, and a second through silicon via <b>201</b>B is formed near a center of the circular formation at block <b>415</b>. In one case, note that the first and second through silicon vias <b>201</b>A and <b>201</b>B may be formed prior to the trench <b>204</b>.

0074A first magnetic material layer <b>207</b> is deposited on the sidewalls of the trench <b>204</b> so as to coat the sidewalls and the bottom surface without filling the trench <b>204</b> at block <b>420</b>. The first magnetic material layer <b>207</b> deposited on the sidewalls forms a first inner closed loop and a first outer closed loop within the trench <b>204</b> at block <b>425</b>.

0075The method includes depositing a first insulator layer <b>208</b> on the sidewalls and the bottom surface of the trench <b>204</b> so as to coat the first magnetic material layer <b>207</b> in the trench <b>204</b> such that the first insulator layer <b>208</b> is on top of the first magnetic material layer <b>207</b> in the trench <b>204</b> without filling the trench. The method includes depositing a second magnetic material layer <b>211</b> (seed layer <b>209</b> is optional) on top of the first insulator layer <b>208</b> on the sidewalls and the bottom surface of the trench <b>204</b> without filling the trench. The second magnetic material <b>211</b> is deposited on the sidewalls and the bottom surface of the trench <b>204</b> so as to coat the first insulator layer <b>208</b> in the trench <b>204</b> without filling the trench. Note that the seed material <b>205</b> may be deposited first when electroplating the second magnetic material <b>211</b>.

0076The second magnetic material layer <b>211</b> deposited on the sidewalls forms a second inner closed loop and a second outer closed loop within the trench. A (top) second insulator <b>228</b> is deposited to fill in the trench <b>204</b> and cover the surface of the substrate <b>200</b>. The method includes etching two separate openings <b>201</b>A and <b>201</b>B in the second insulator <b>228</b> and first insulator <b>208</b> to expose both the first through silicon via <b>201</b>A and the second through silicon via <b>201</b>B through the second insulator <b>228</b>.

0077For illustration purposes, various deposition techniques are discussed below and can be utilized in embodiments, as understood by one of ordinary skill in the art. Thin film deposition is the act of applying a thin film to a surface which is any technique for depositing a thin film of material onto a substrate or onto previously deposited layers. Thin is a relative term, but most deposition techniques control layer thickness within a few tens of nanometers. Molecular beam epitaxy allows a single layer of atoms to be deposited at a time. Deposition techniques fall into two broad categories, depending on whether the process is primarily chemical or physical. Chemical vapor deposition utilizes a fluid precursor that undergoes a chemical change at a solid surface, leaving a solid layer. Chemical deposition is further categorized by the phase of the precursor and examples of chemical deposition include, but are not limited to: plating; chemical solution deposition (CSD) or chemical bath deposition (CBD); spin coating or spin casting; chemical vapor deposition (CVD); plasma enhanced CVD (PECVD); atomic layer deposition (ALD); and so forth.

0078Physical vapor deposition (PVD) uses mechanical, electromechanical, or thermodynamic means to produce a thin film of solid. Examples of physical deposition include but are not limited to: a thermal evaporator (i.e., molecular beam epitaxy); an electron beam evaporator; sputtering; pulsed laser deposition; cathodic arc physical vapor deposition (arc-PVD); electrohydrodynamic deposition (electrospray deposition); reactive PVD; and so forth.

0079Note that eddy currents are electric currents induced within conductors by a changing magnetic field in the conductor. These circulating eddies of current have inductance and thus induce magnetic fields. The stronger the applied magnetic field, the greater the electrical conductivity of the conductor, or the faster the field changes, then the greater the eddy currents that are developed and the greater the fields produced.

0080The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.

0081The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.

0082The diagrams depicted herein are just one example. There may be many variations to this diagram or the steps (or operations) described therein without departing from the spirit of the invention. For instance, the steps may be performed in a differing order or steps may be added, deleted or modified. All of these variations are considered a part of the claimed invention.

0083While the preferred embodiment to the invention had been described, it will be understood that those skilled in the art, both now and in the future, may make various improvements and enhancements which fall within the scope of the claims which follow. These claims should be construed to maintain the proper protection for the invention first described.